const numberArr : number [] = [1,2,2,3];
const stringArr : string [] = ['1','2'];
const undefindArr : undefined [] = [undefined,undefined];
const arr : (number | string) [] = [111,'222',333];

//type alias 类型别名
type Lady = {name:string,age:number};
// class Madam {
//    name:string;
//    age:number;
// }

const xiaojiejie:Lady[] = [{name:'胡一菲',age:18}]
//const xiaojiejie:Madam[] = [{name:'胡一菲',age:18}]